1. Field
The present disclosure relates generally to circuits and, in particular, to circuits with transistors. Still more particularly, the present disclosure relates to a method and apparatus for controlling the operation of circuits with transistors.
2. Background
A circuit module is comprised of one or more electronic components. These components may be, for example, resistors, transistors, capacitors, inductors, diodes, or other components that may be connected to each other through wires or traces. A circuit module may also be referred to as an electronic circuit.
Although circuit modules may be formed from discrete components connected to each other by wires, electronic circuits are more commonly formed on a printed circuit board or on a semiconductor as an integrated circuit.
Circuit modules are used for many different purposes. For example, circuit modules may be used in power applications. For example, circuit modules may be used to convert direct current to alternating current, alternating current to direct current, and from direct current to direct current as examples of some uses. These types of circuit modules may be used to provide power to other electronic circuits for devices.
In some cases, a circuit module that provides current to power other circuits may not be configured to a desired level of current. With this situation, another circuit module may be used that provides a higher level of current. Another solution may involve connecting two or more circuit modules in parallel to provide the desired level of current.
Operating circuit modules in parallel to provide a desired level of current may be challenging depending on the precision desired for the current level generated by the circuit modules. The differences in current generated may be caused by the variation in values for parameters in manufacturing the circuit modules. These parameters represent electrical properties for the components in the circuit modules.
With unbalanced current sharing, undesirable results may occur. For example, unbalanced sharing by electronic modules may result in at least one of overheating, a presence of circulation currents, damage to transistors, increase losses, de-rating of the circuit modules, or other undesirable results.
Design constraints may be used in an attempt to reduce variations in values for parameters. These design constraints may include matching components. For example, a common gate drive circuit may be used to parallel connected transistors. Separate gate drive circuits may be used that are very closely matched. Closely matched gate drive resistors may be used. Homogenous sinks may be used to cure parallel circuit modules to reduce temperature differences between circuit modules. Closely matched transistors may be used in constructing circuit modules. Common mode chokes may be used in the gate drive circuit and the rewiring impedance for transistors may be reduced.
These and other design constraints may be used in an attempt to reduce the variations in parameters during the operation of a circuit module. These types of constraints, however, may not be able to reduce the variations in values for parameters as much as desired.
Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.